A severe shuttle effect and a poor sulfur utilization rate impede the application of Li-S batteries, and the rational design of sulfur host can alleviate these problems. Herein, we synthesized MoS2-modified three-dimensional (3D) porous carbon nanofibers (MoS2@CNF) as a sulfur host. The porous structure can offer channels for the transport of Li+ while accommodating more active materials. The doped MoS2 has strong chemisorption and electrocatalytic synergistic effect on polysulfide, which can accelerate the conversion of polysulfide. Consequently, these structural and chemical advantages allow S@MoS2@CNF cathode to achieve excellent electrochemical performance.